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Solving for base angles in a congruent triangle

  1. Nov 27, 2013 #1
    1. The problem statement, all variables and given/known data

    Solving for base angles in a congruent triangle
    One of the base angles in a congruent triangle is 3x+5
    The other base angle is unknown
    The remaining angle is x+16.

    2. Relevant equations

    See attached PDF

    3. The attempt at a solution

    Because two base angles in a congruent triangle are the same and I have been given one of them I did the following:-

    3x+5 = 3x+5 (I then tried to solve for x but this cancels out to 0.)

    I want to know why this is the case, i think it is because i have 2 unknown variables but only1 equation.
     

    Attached Files:

  2. jcsd
  3. Nov 27, 2013 #2

    Dick

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    As you said, the other base angle is 3x+5. You need to use something else. What's the sum of all of the angles of a triangle?
     
  4. Nov 27, 2013 #3
    The sum of the interior angles of a triangle is 180Degrees.

    But i want to know if making 3x+5 equal to itself 3x+5 (3x+5 = 3x+5) am i trying to solve for 1 unknown with 1 equation or am i trying to solve 2 unknowns with 1 equations?
     
  5. Nov 27, 2013 #4

    SteamKing

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    Setting 3x + 5 equal to itself implies 1 = 1. You need some other piece of information.
     
  6. Nov 27, 2013 #5

    Dick

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    As you said, the sum of your angles is 180 degrees. Write down an equation that expresses that.
     
  7. Nov 27, 2013 #6

    Curious3141

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    Also, why are you calling it a "congruent triangle"? Don't you mean "isoceles triangle"?

    To expand on what others have said, what is the sum of the 3 angles in terms of x? Equate that expression to 180 degrees and solve.
     
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